Vagina. — The canal leading from the uterus to the external 

 genital opening in female mammals. 



Vagina, Artificial. — A double walled rubber tube to which 

 is fitted at one end, a glass receptacle and which is used in 

 artificial insemination in collecting semen from the male. The 

 space between the double walls is usually filled with warm 

 water. 



Variance. — (a^). The mean squared deviation from the mean: 

 S(d2) 



(J" =. r— where d is the difference between an observation 



n-1 



and the mean, n is the total number of observations and S rep- 

 resents summation over all the squares of the differences. 



Variant. — An organism differing slightly from the type. 



Variations. — The differences between the individuals in any 

 given related population. 



Variegation. — Spots or patches of different colour; generally 

 a mosaic or chimaera but sometimes caused by disease or other 

 environmental factors. 



Variety. — A group of strains or a single strain which, by its 

 structural or functional characters, can be differentiated from 

 another group. 



Vasa deferentia. — A continuation of the epididymi lying 

 between these and the urethra. In some animals each vasa 

 deferens has an enlargement (the ampulla of Henle) which 

 functions as a storage place for spermatozoa. 



Vasectomy. — A form of sterilization accomplished by the 

 removal (or ligature) of a small section of each spermatic 

 duct. 



V-chromosomes. — Chromosomes with two arms, i.e. medio- 

 centric chromosomes. 



Vegetative Apogamy. — The production of a sporophyte di- 

 rectly from the vegetative cells of the gametophyte without any 

 sexual act. 



